Is this the warmest sleeping bag ever made?

I am currently waiting for a PHD sleeping bag to be made for me for winter camping. I ordered it sometime ago in the sale that has just finished. The office admits that they are a bit behind with the orders and I should get it soon. I wonder whether it was held up because of all the gear that they were making for Sir Rannalph Fiennes team’s  winter crossing of  Antarctica. Look at the slideshow on the PHD website for a sleeping bag rated down to below minus 70C!  The breathing hole is pretty radical  – not quite what I have on order, a sleeping bag for just minus 10C!  The slide show can be found here

This entry was posted in Gear and tagged , . Bookmark the permalink.

36 Responses to Is this the warmest sleeping bag ever made?

  1. Martin Rye says:

    I hope it works for you. I read mixed feedback on PHD bags. Some say not as good as claimed, and some rate their kit. I had a down jacket from them years ago and sold it on. Not a fan.

    • backpackingbongos says:

      I am one of those that say the ratings are optimistic. Well made bits of kit but ratings are way out.

      • Martin Rye says:

        You say 500g box wall bag from them with a DriShell outer is ok -5/6, but others say -14? Allowing metabolic variations, sleeping mat, location (cold air sinks etc) it still seems to me too vast a gap. Others have said they found PHD Min500 not as warm as hoped. As I know you James and you have a comparison bag with 400g of down (not as high grade) I think your right.

        Don’t forget most bags have a 50/50 split of down stuffing. Something I feel is ineffective. You crush the down you lie on.

        In the end sleeping warm is more than a lot of down stuffed in some baffles. Food, water, a hot water bottle, insulating seeping mat and location all factor.

      • Martin, I have an Alpkit Pipedream 400. With a PHD down jacket on and an Exped Down mat, I slept fine at a genuine -10C night, apart from my nose which when I woke up in the morning I thought I had frost nip on it – it hurt so much. The only thing sticking out! I agree with you Martin there are a lot of factors which will affect this rating. The person, additional clothing, the mat, warm food and drink before you go to bed etc etc.

        The bag on order is a 500 Mimim with Drishell. I will soon see whether my selection was right !!

      • James I will soon found out if I can it before this cold weather finishes

    • Hi Martin, I like my PHD Down jacket very much. I don’t know about sleeping bags – I will soon see!

  2. -maria- says:

    I’ve been planning on knitting a balaclava with a breathing hole like the PHD have on this -70C bag! It would be for cold winter nights. Hope you get your sleeping bag soon; I’m still pondering whether to buy a winter down sleeping bag or a synthetic sleeping bag to beef up my current down sleeping bag. That is one-in-all vs. modularity… The modularity would be a nice option if some of the nights are beeing slept in a hut, and the synthetic bag wouldn’t suffer from moisture that much. But on the other hand, a single down bag would pack smaller… Oh, decisions, decisions…

  3. Good luck with your new bag Mark! I personally know nothing about PHD, but it’s always hard trying to decide what’s the best thing to spend your hard earned cash on, isn’t it?
    They had a report about the Antarctic trip on BBC News 24 this morning, but it was just at the wrong time for me – I had to leave for work half-way through it 🙂

  4. terrybnd says:

    I’ve heard quite a few folk say similar things to Martin and James. Alas, I’ve got no personal experience of their kit. However, the fact you can customise their kit is excellent. I suppose with reference to the above points you could always ask for differential fill – and it shouldn’t make any difference to cost.

    That sleep bag in the slideshow…Ha! Crikey! That’s amazing. I want to have a go in it! 🙂

  5. Eddie says:

    From a weight/performance/price perspective, you won’t be disappointed. Providing you have got all of the other requirements for a good nights sleep sorted, whether it will keep you warm at it’s indicated rating is purely up to your physiology. Same goes for everybody. PHD say quite a bit about their ratings on their site.
    I have used a Minim 300 and a Diamir 500 over the years and found their ratings to be accurate. The quality of the Diamir in particular was absolutely first class, but that is from the HT range and is much more expensive than the Minim types. But there was nothing wrong at all with the Minim either.
    Enjoy your new bag and (hopefully) comfy nights.
    You can’t please everybody, but they please most folk.

    • Hi Eddie, thanks for dropping by. Thanks for your comments. I have found PHD to produce excellent down clothing, I have the Minimus Down jacket and the down vest and I rate them. I am looking forward to using the Minim 500. I will will keep people posted.

  6. AlanR says:

    There’s only one way to find out Mark, Leave off the clothes and camp at -10 in the new bag. Lets see what you think then. I have one too from last year, i have never posted on it as yet because i have only been down to -7C in it so far.

  7. Alan R says:

    I have only been down to -7 on 2 nights. Being honest it isn’t a fair test because i was base camping and not backpacking. I never sleep with clothes on but on this occasion i did have an extra thermal layer underneath my UL down mat. I wouldn’t have had this on a backpacking trip.
    I was ok at -7, i slept well but Sheila was cold and needed more insulation. Ladies do need more insulation than men i believe.
    From what little i have learned i would say -10 would be the absolute limit. But like i said, i sleep naked. I’m not one who carries extra gear to substitute for inadequate (Light) spec’d bags. I find this pointless. But i don’t want to start a row about that philosophy.

    • Alan, I generally wear a light base layer, usually Rohan Silver Core. If it goes down to -7C then it will be fine for me for most situations. The coldest I have slept is -10C, if I feel a bit cold I can wear my down jacket. I always carry that in the winter so its not additional weight. My understanding is that females need at least an extra 5C degrees worth of insulation.

  8. Martin Rye says:

    Out of interest Mark my winter bag is a RAB Alpine 600. 600g of 800 fill power down, and endurance outer. RAB say -10. Trapezoidal baffle chamber design also which is better than box baffles. Both my down bags have that now. But PHD say 500g down to -10. See my point about their claims. I also agree with Alan. Good spec bag is the way based on the conditions. Too many take light bags and add down jackets and down trousers to sleep warm, when a bit more down in a bag will keep you warm and weight is less than all that extra down clothing. Better a warm bag and light insulting top for the days. Get in your bag at camp if cold. Walk longer, camp, sleep get up and walk.

    • Hi Martin, I will be interested to see how I sleep with this bag and whether 500g of 800 fill down will be adequate. I haven’t sleep many times at -7C or less so probably the bag will be good for most winter nights. I do agree with you and Alan regarding not carrying unnecessary insulation and this depends on the type and weight. I think I have my weights right on this, but correct me if I have got the weights or insulation wrong.

      Your set-up: Alpine 600 @ 1.15kg + Rab Generator pull-on @ 365g (I think you have this) = 1.515kg

      My proposed: PHD Minim 500 with full zip@ 890g + PHD Minimus down jacket@ 480g = 1.370kg or using my rab generator pull-on@ 365g = 1.255kg

      So if I find that the sleeping bag does not go down -10C, both PHD products will weigh less, not much and to be honest, I not too much of a gram counter these days and would equally be happy with your set up as well.

  9. Martin Rye says:

    Very few sleeping bags have above 50% down to material weight ratio Mark. 56% down seems very high. I would wait to you get it for the true weight.

    I use my down Jacket as well (WM one, and have summer down top which is very light). Need a warmer winter one. I also have no inner tent. Having seen to many not need them I am happy with just my single skin. Maybe a MLD bivy. Either way it’s not the total weight that is the goal, it’s what do I need. RAB bag is proven as my Mate Terry tested his to death. I have been cold in it BTW. Wrong sleeping mat. You live, you learn. Had it a while and very happy with it bar my own mistake on mat selection.

    True weight of the Alpine is on a comment from me on Terry’s review. Also I am going to guess yours will be? ….950g if no collar and zip. No collar is a mistake for sleeping cold IMHO. So my RAB with its hard weather resistant shell, collar and frills and spills might be a shocking 1.2kg nearly, but those features all add up if I add a winter mat.

    Also add a collar, zip and make it a long the PHD bag will not far of the RAB one – 100g of down. People get wowed by weight of PHD bags until they note the size; unlike RAB bags good to 6,4.

    A good nights sleep is something I have come to realise is not worth skimping on weight. I also thing for the depths of winter 800g is more like what we need. All bags are made different and weight will be varied as a result. Mesh baffles trapezoidal baffles in the RAB bag for example I recall. All little things that hold the Down in place (PHD is continues baffles I think?) but add warmth. Sometimes the detail is the dividing line for performance. Hope your bag is all you hoped for.

    • Martin you make some good comments here. I maybe I have been seduced by PHD weights. I was also seduced by the price as well as I had 20% off normal price, so maybe I will have to compromise somewhere. I think I do sleep warm as I was warm enough at -10C with a -3C bag and a PHD down jacket. I am interested in you comments about having no inner tent. That night I slept in my Soulo and measurement outside of the tent was -10C. I didn’t measure inside. I mention this because a video review of the Soulo from the Pacific NW suggested that there was as much as a 20F difference between the inside and outside of the Soulo on a overnight camp in snow. That seems a lot to me but I would like to measure this to see what difference there is if any. This would be significant to what sleeping bag rating one would take.

      • backpackingbongos says:

        Mark, I always find that the temperature inside a tent with an inner is significantly warmer than inside a single skinned tent. The coldest I have ever measured inside my tent is -5c, I have no idea of the temp outside but it was bloody cold. On recent trips where it has fallen below freezing and water etc has frozen in my porch, the temp has not dropped below freezing inside the inner. Having a dog in there helps!
        The downside of zipping yourself in an inner is that you get an early shower, Akto, Scarp or Voyager all get pretty damp after 16 hrs inside in mid winter unless its windy.

      • I would agree James, my last trip in the peaks after being zipped up in my Power Lizard was plenty of ice crystals in the morning, which was fine until I fired up the stove. I am not so worried up this as I tend to get up and get going fairly sharpest in the morning – so it wakes me up:)

  10. Martin Rye says:

    I don’t know about a huge difference in temp Mark. There is some. But many use SL3 in winter alone with no inner. Think Andrew Skurka and co. Do they? ‘No’. Do the math. Inner say adds 500g, or I take a warmer down jacket and as I have one already I am gaining 150g of down. More warmth, less weight. Also in cold those puffy pants and warmer jacket give me more than an inner. I can done the jacket at stops and camp. I cant put on an inner for a tent or shelter. Down clothing is going to be warmer and offer me more options. Also DaveC uses single skin mids in winter. Real cold conditions. He pimped his mid with a stove for winter but that is to dry kit out more than keeping him warm. Read his blog about it. I might get lost with his views at times but his kit stuff and trips are superb. He is without a doubt pushing ideas on backcountry travel and light kit while backpacking.

    Also I have had many nights with ice forming inside the inner tent. So why do I need it? Read up on the likes of Skurka and co and how he copes with winter. Luc Mehl on fast and light winter travel is interesting if radical. Look at Joe Newton and Jorgan on their winter trips with single skin tents.

    I want to build on skills and do more winter travel Mark. Light winter travel appeals. I feel a winter Scotland trip is a must, and also skills built on that open up other trips. Lots to learn and find out on winter travel.

    • backpackingbongos says:

      I was just going from personal experience Martin. I tend to backpack quite a lot.

      • I can learn a lot from you and Martin because you both have more experience than me. I need to do more trips – always difficult with family and work for me, but I going to try in the next week or so and over the Xmas period.

    • Interesting stuff there Martin, do you have some links to DaveC? I know about Joe. Like you I would like to do more backpacking in general particularly in winter.

  11. Martin Rye says:

    I am not disputing inners add warmth James, just pointing out they are not used by many in winter and do they offer all that is assumed they do? End goal is to be warm in winter at camp. Clothing and sleeping bag are best for that. All my UK wild camps before July had negative night time conditions and I used a Single skin shelter. Why I got cold was not having an inner. My sleeping mat was the issue. Also other camps last year in cold I had no inner.

  12. Martin Rye says:

    Luc on winter travel foremost Alaskan adventure/explorer right now I expect.

    DaveC blog to go through is here at

    Also this walk to a new home depths of Alaska in winter with a MLD single skin Mid.

    Want to do a winter walk? Email me.

  13. korpijaakko says:

    Sorry, I was too lazy to read all the comments but some random thoughts:

    It’s really, really hard to compare the warmth of sleeping bags. A simple test on the insulative properties is quite easy to perform (EN13573) but as most things in life, this is also more complicated than a simple number. I’ve noticed a huge variations in the experienced warmth of any sleeping set up between different nights – even though the set up and temperatures would be about the same! So it’s hard to tell without personal long term testing (the more nights out, the more you’ll know). I’d say that I have nowdays a good idea about what I need for winter conditions (down to -40C, colder yet to be explored when I find it…) I’d say go out and try. Generally a reasonably warm down bag supplemented with outer synthetic bag or quilt is a good idea if you’re out in witner conditions for longer than a night or two. (Modularity = adjustability = comfort + helps moisture management.)

    I find it strange that PHD doesn’t test their bags according to the EN standards. It gives reasonably good figures for comparing bags meant to be used down to -20C or so (below that the test arrangement starts to fail for reasons unknown to me). Is it because the kit is not up to the promises? Don’t know as I only have a down vest from PHD but that’s a superb piece of kit. I also had an incredibly warm Cumulus sleeping bag ( and even though they are not tested according to the standard the t emp rating was spot on to me. They also custom the bags on request.

    I don’t know if the bag PHD made for Ran and co is the warmest ever made but looks like it’s up to the job. I like the “funnel” around the face a lot. Fjällräven has also nice looking bag coming up: (Though it’s missing the additional seal on neck! A good hood is no excuse to leave that one out!)

    PS. Typically a general double walled tent is usually 5 to 10 degrees C or so warmer than the outside temperature (again depending on things) but haven’t compared the difference to single skin shelters. There should be a difference though. And a good seal to keep out drafts and drifting snow but still having adequate ventilation is the key.

    • Hi Jaakko. I have reproduced PHD’s thoughts below from the website on their ratings:

      So at PHD, knowing we can’t eliminate the uncertainties, we have tried to keep it simple. What we quote for each of our bags is: a single minimum temperature (we call it a Typical Operating Temperature or TOT for short) at which you should be able to get a night’s sleep under normal circumstances.

      By ‘normal’ we mean:

      you’re in shelter
      you have eaten normally
      you have sufficient ground insulation
      your bag is dry
      you’re not a ‘cold sleeper’
      you’re wearing clothing appropriate to the conditions: below 0°C (32°F) we would expect anyone to wear at least thin thermal underwear; below -25°C (-13°) at least thick thermals.
      And while we’re describing what’s normal, we should add that if you’re an experienced ‘hardy’ type, you can probably take the bags below their quoted temperatures by about 5°C (9°F).

      Of course I think that different people will react to different temperatures, some will feel cold in a 500g down bag and others may be too hot. When I receive my PHD bag it will be the first from the company, but like you I have a down vest from them and and down jacket which I feel are excellent products. Under normal circumstances I am unlikely to meet the temperatures you meet on your winter expeditions. PHD do a combo product which a down bag can fit inside to take the bag to lower ratings. I will take a look at your links and thanks for your comments.

    • Jaakko I had a look at the Fjallraven video. Excellent looking design and one wonders why this type of design is not more widely available on sleeping bags.

  14. Martin Rye says:

    Thanks for sharing here Jaakko. Your experience of severe cold Vs our damp cold is helpful. Another Link Mark.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s